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Thread: Light frequency modulating device?

  1. #1 Light frequency modulating device? 
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    hello,

    I was wondering,
    Would it be possible or is there a device that can modulate the frequency of light?
    This would be analog to frequency modulators for sound.
    With the resulting device you should then be able to "scroll" through all colors.

    This could be used for mood lights, while not having to use multiple lightsources to mix colors.
    Maybe it can be of use to check for eye problems (see if someone can still see the whole spectrum)
    I guess it would also be possible to make Bluray lasers that can read dvd and cd by changing the frequency of the laser? (for now, they still use different lasers right?)
    thanks!


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  3. #2  
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    You can modulate electromagnetic waves in the radio frequency - that's FM. But lasers are based on a specific element's electron transition from one quantum level to another. I wouldn't know how to modulate that.


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  4. #3  
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    That would indeed be hard,

    so the only option is probably just a simple filter in front of the light source?
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  5. #4  
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    One method is to direct the beam through a piezoelectric crystal. As the crystal vibrates with the input signal, it expands and contracts, changing the light frequency slightly. However, I don't know how one would shift the frequency enough to change the visible range.
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  6. #5  
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    interesting, thanks!
    i found something, called frequency doubling, apparently used in LaserTV.
    Because only red lasers are powerfull enough while having a good lifetime, the green and blue colors are achieved by frequency doubling.
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  7. #6  
    Forum Professor Wild Cobra's Avatar
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    Quote Originally Posted by pitou777
    interesting, thanks!
    i found something, called frequency doubling, apparently used in LaserTV.
    Because only red lasers are powerfull enough while having a good lifetime, the green and blue colors are achieved by frequency doubling.
    I guess there are some materials that can do that. When I was in the communications field, we used doublers and triplers for microwave frequencies. No reason the same principles won't work at light frequencies.
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  8. #7  
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    off course there's still a difference between switching to 1 different frequency, and being able to choose every frequency
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  9. #8  
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    you can in the sense that a laser of one color is used to pump die colors,


    Theoretically though wouldn't a particle accelerator change color of particle after hitting light speed then increasing energy?
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  10. #9  
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    If you want to do this practically, then your best shot is to use Red-Green-Blue mixing of three light sources. Just have each light source's contribution modulate in intensity.

    Another possibility might be to use a white light source with filters, to filter out all the light that doesn't fit into exactly the band you want. I'm not sure how well that would work, because I'm not sure there's any such thing as perfectly white light. (Light where all frequencies are equally represented, without skipping any.)

    The color of light after it has been emitted is really hard to change.
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